Road crashes involving young Australians have an often overlooked cause - the significant number of teenagers who deliberately harm themselves.

Self harm a factor in youth car crashes

Road crashes involving young Australians have an often overlooked cause - the significant number of teenagers who deliberately harm themselves.

A major NSW-based study has found those young people who admit to self-harming behaviour were also at a much higher risk of being involved in a serious car crash.

"Self-harm is a significant issue for young people in Australia," said Dr Alexandra Martiniuk who led the study at The George Institute for International Health.

"We know that this also impacts considerably on young driver safety, as we found those drivers who engaged in self-harm were at a 40 per cent increased risk of a crash."

Self-harm behaviour is often deliberate cutting or burning but also attempted hanging or poisoning.

The research took in almost 21,000 young drivers who held P-Plates and were aged 17 to 24.

Just four per cent admitted to self-harming behaviour. These young people were found to have a 40 per cent higher risk of being involved in a crash during a two-year study window.

Dr Martiniuk said it was unclear whether these crashes were deliberate - further attempts at self-harm - or whether they were the result of these young people having a lower regard for personal safety or increased risk-taking.

What was known was these crashes often involved multiple vehicles.

"This amplifies the danger from these crashes, as it's not only the safety of young drivers who engage in self-harm (that is) at an increased risk but the safety of all road users," she said.

The study found self-harm was more common among young women, particularly those who were Australian-born and who lived in regional areas and who reported higher levels of drug and alcohol use.

Dr Martiniuk also said for those young people who admitted to self-harm, many more were suspected to keep it a secret.

The four per cent who admitted to it would be "on the lower end of what we think is going on".

"Studies around the world have shown that people in this age group who self-harm range from five to 17 per cent of the population," Dr Martiniuk said.

"It's quite hard to get a measure of this around the world because very few people admit to the fact that they self-harm ... (and) the youth involved are very unlikely to seek help."

The study showed the need for improved methods of identifying young people who self-harm, Dr Martiniuk said, while young driver programs should take this additional risk factor into account.

The research was undertaken as part of the DRIVE study, funded by the National Health and Medical Research Council, NRMA and the Roads and Traffic Authority of NSW.